Latching key mechanism

ABSTRACT

Two depressible key members of a key mechanism may be latched at an actuated position by two identical latch members which are inverted relative to each other for latching association with different key members and arranged for sliding movement transverse to the depressible movement of the key members. Upon depression of a first key member, a corresponding tab engages a first beveled surface of the associated latch member and cams it aside against the urging of a spring until the tab moves beneath a hook formation whereupon the spring moves the associated latch member to a rest position abutting a stop with the hook formation latching the tab to hold the first key member at the actuated position. The depression of the second key member brings a corresponding tab into engagement with a second beveled surface of the latch member associated with the first key member and cams the latch member aside to release the first key member from the actuated position while the second key member is latched at the actuated position in a manner similar to the first key member. The inverted relationship of the identical latch members places the first beveled surface of one latch member adjacent the second beveled surface of the other latch member to provide simultaneous movement in opposite directions upon depression of a key member and to prevent either of two simultaneously depressed key members from being latched at the actuated position.

United States Patent [1 1 [111 3,861,235

Wenderoth Jan. 21, 1975 LATCHING KEY MECHANISM may be latched at an actuated position by two identi- [75] Inventor: Karl Wendemth, Bad Vilbe], cal latch members whtch are inverted relative to each Germany other for latching association with different key members and arranged for sliding movement transverse to [73] Assigneez A rw r v rm- H inr h Kl y r, the depressible movement of the key members. Upon N g, Germany depression of a first key member, a corresponding tab [22] Filed: Oct 29 1973 engages a first beveled surface of the associated latch member and cams it aside against the urging of a PP 410,517 spring until the tab moves beneath a hook formation whereupon the spring moves the associated latch O F member to a rest position abutting a stop with the [3 1 Apphcam y Data hook formation latching the tab to hold the first key Nov. ll, 1972 Germany 2255336 member at the actuated position The depression of the second key member brings a corresponding tab 2% '6 g /3 2g g2 into engagement with a second beveled surface of the l037 5 latch member associated with the first key member 1 0 can 200 5 j 235/145 and cams the latch member aside to release the first I key member from the actuated position while the second key member is latched at the actuated position in [56] References Clted a manner similar to the first key member. The in- UNITED STATES PATENTS verted relationship of the identical latch members 2,154,778 4/1939 Schnell 200/5 E X places the first beveled surface of one latch member 2,213,845 9/1940 M y et al 8 PB X adjacent the second beveled surface of the other latch 2,31 Zimmerman 3t fil member {0 provide imultaneous movement in ppo- 2,451,150 10/1948 Brian 74/483 PB x Site directions upon depression f a key member and Davis to prevent either of two simultaneously depressed key Primary ExaminerAllan D. Herrmann Attorney, Agent, or Firm-Joseph R. Spalla [57] ABSTRACT Two depressible key members of a key mechanism members from being latched at the actuated position.

11 Claims, 3 Drawing Figures -w t t PATENTEDJANZI I975 3,861,235

Fig..l

LATCIIING KEY MECHANISM This invention relates to a key mechanism for a business machine, and more particularly to a key mechanism wherein the depression of one key to an actuated position releases another key previously latched at the actuated position.

In the past, key mechanism have been provided wherein depressed keys are latched in an actuated position by either a latching bar or a spring loaded latching slide. Such arrangements are shown, for example on Page 255 et seq. of a book entitled Structural Elements of Precision Mechanics by Richter and v. Voss, published by Verlag Technik Berlin 1957. However, such key mechanisms are disadvantageous for some machines because more than one key can be actuated at the same time and remain latched.

Accordingly, an object of the present invention is to provide a key mechanism wherein the actuation of a key releases a previously latched key and prevents more than one key from being latched in an actuated position.

Still other objects, features and advantages of the present invention will be apparent to those skilled in the art from a reading of the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic illustration of a key mechanism constructed in accordance with the present invention and illustrating the mechanism in a rest condition;

FIG. 2 shows the key mechanism of FIG. 1 with one of the keys latched in an actuated position; and

FIG. 3 is a partial diagrammatic and exploded view of the key mechanism of FIG. 1.

Referring now in detail to the figures in the drawing, there is shown a key mechanism, generally indicated 11, including a pair of key members 13, located in spaced relation to each other and normally biased by suitable means, not shown, to a raised rest position as shown in FIG. 1. Each of the key members 13, 15 are depressible to an actuated position, as shown in FIG. 2, and may be held at the actuated position by a latching arrangement, which includes two identical latch members 17, 17 each associated with different key members 13, 15 respectively. Each of the key members 13, 15 has a projection 13, 15' respectively, for engaging the latch members 17, 17', and each of the latch members 17, 17 has a hook formation 19, 19 respectively, for latching engagement with the projection 13', 15' of the associated key members 13, 15. Upon depression of one of the key members, for example 13, to the actuated position, the latch members 17, 17 are moved so as to latch the projection 13' under the associated hook formation 19. Upon depression of the other key member 15 to the actuated position, the latch members 17, 17 are again moved so as to release the previously actuated key member 13 and latch the key member 15 at the actuated position in a similar manner. Since the latching arrangement is identical for both key members 13, 15, similar reference numbers have been placed on similar portions thereof. Moreover, the biasing means for the key members l3, 15 as well as other parts of the key mechanism 11 are not shown since they form no part of the invention and may be desirably conventional.

As shown, the key members l3, 15 are supported on a machine frame 21 for movement in a vertical direction, and the latch members 17, 17' are slidably received in guide ways, generally indicated 23, of the machine frame 21 for longitudinal movement in a horizontal direction. The projections 13', 15 of the key members 13, 15 are in the form of tabs extending laterally across both of the latch members 17, 17', and the identical latch members 17, 17' are inverted relative to each other so as to place the hook formations 19, 19 adjacent the associated projections 13', 15. Each of the latch members 17, 17' has a beveled surface 25, 25' leading to the hook formation 19, 19' for engagement by the tab 13', 15 respectively, of the associated key members 13, 15 and another beveled surface 27, 27' leading to a vertical edge 29, 29 of a cutout for engagement by the tab 13, 15' respectively, of the other key member 13, 15. A central stop abutment 31 is formed on the machine frame 21 between the key members 13, 15, and each of the latch members 17, 17' have a shoulder 33, 33' which is urged against the abutment 31 by resilient biasing means in the form of a spring 35 which is disposed in central openings 37, 37' of the latch members 17, 17' and stretched therebetween. The latch members l7, 17 may be formed as metal stampings and provided with protruding dimples 39 to separate each other for easy sliding contact.

When the key member 13 is depressed to the actuated position as shown in FIG. 2, the tab 13' contacts the adjacent beveled surfaces 25, 27' and cams the latch members 17, 17' in opposite directions against the urging of the spring 35. As the tab 13 moves past the beveled surface 25 and beneath the hook formation 19, the latch member 17 snaps back against the central stop 31 with the hook formation 19 moving over the tab 13 to hold the key member 13 at the actuated position. At the same time, the tab 13' moves past the beveled surface 27 onto the vertical edge 29' so as to prevent the latch member 17 from returning to its normal rest position with the shoulder 33' abutting the central stop 31.

If the other key member 15 is now depressed to the actuated position, the corresponding tab 15' engages the beveled surface 27 and imparts a camming movement to the latching member 17 so as to remove the hook formation 19 from the tab 13, thereby enabling the key member 13 to return to the raised rest position as shown in FIG. 1. At the same time, the tab 15' engaged the beveled surface 25 and imparts a camming movement to the latch member 17' against the urging of the spring 35 until the tab 15 moves beneath the hook formation 19', whereupon the latch member 17' snaps against the central abutment 31 to latch the key member 15 at the actuated position in the same manner as previously described in connection with the key member 13.

If both key members l3, 15 are depressed at the same time, then neither key member 13, 15 will be latched at the actuated position since the corresponding tabs 13', 15' will move into engagement with the vertical edges 29, 29' of the latch members 17, 17 so as to prevent the hook formations 19, 19' from latching with the tabs 13', 15 to hold the corresponding key member 13,

15 at the actuated position. However, if one of the key' members for example 15, is returned to the raised rest position, then the latch member 17 associated with the other key member 13 will snap against the central abutment 31 and latch the hook formation 19 over the tab 13 to hold the other key member 13 at the actuated position.

What is claimed is: 1. A key member comprising: a first key adapted to be moved between a rest and an actuated position, a second key adapted to be moved between a rest and an actuated position, first latching means adapted to retain said first key in the actuated position, second latching means adapted to retain said second key in the' actuated position, means resiliently biasing said first and second latching means toward each other, means associated with said first and second latching means whereby when the first key is moved to the actuated position the second key will assume a rest position and when the second key is moved to the actuated position the first key will assume the rest position. 2. The key mechanism of claim 1, wherein the first and second keys are each provided with a flange, and said means associated with the first and second keys are camming surfaces disposed in the first and second latching means responsive to the motion of the flanges provided with the first and second keys. 3. The key mechanism of claim 2, wherein said first and second latching means are provided with means for retaining the first and second keys in the rest positions.

4. The key mechanism of claim 3, wherein said retaining means are hook formations disposed in the first and second latching means.

5. A key mechanism, comprising: first and second key members each arranged for a depressible movement from a rest position to an actuated position and having a flange formed thereon, a latch member moveable relative to the depressible movements of said first and second key members and having a hook formation for latching engagement with the flange of said first key member at the actuated position, said latch member having first and second camming surfaces for engagement by the flanges of said first and second key members respectively with the first camming surface leading to the hook formation, said latch member undergoing a camming movement upon engagement of the first camming surface by the latching flange of said first key member during a depressible movement of said first key member to the actuated position, resilient biasing means urging against the camming movement effected by the depression of said first key member and moving the hook formation into latching engagement with the flange of said first key member upon movement of the flange past the first camming surface so as to hold said first key member at the actuated position, and said latch member undergoing another camming movement for releasing said first key member upon engagement of the second camming surface by the flange of said second key member during a depressible movement of said second key member to the actuated position,

. 6 another latch member moveable relative to the de pressible movements of said first and second key members and having a hook formation for latching engagement with the flange of said second key member at the actuated position, said other latch member having first and second camming surfaces for engagement by the flanges of said first and second key members respectively with the second camming surface leading to the hook formation, said other latch member undergoing a camming movement upon engagement of the second camming surface by the latching flange of said second key member during a depressible movement of said second key member to the actuated position, said resilient biasing means urging against the cam ming movement effected by the depression of said second key member and moving the hook formation into latching engagement with the flange of said second key member upon movement of the flange past the second camming surface so as to hold said second key member at the actuated position, and said other latch member undergoing another camming movement for releasing said second key member upon engagement of the first camming surface by the flange of said first key member during a depressible movement of said first key member to the actuated position. 6. A key mechanism according to claim 5, and further comprising:

first and second guideways each receiving portions of said latch member and said other latch member for slidable movement relative to each other, a central stop abutment located between said guideways, said latch member having a shoulder formed thereon for engagement with said abutment, said other latch member having a shoulder formed thereon for engagement with said abutment, and said spring urging said latch member and said other latch member into engagement with said abutment. 7. A key mechanism according to claim 5, wherein said latch member and said other latch member have identical configurations.

8. A key mechanism according to claim 5; said latch member and said other latch member being arranged for slidable movement relative to each other and undergoing camming movements in opposite directions, and said resilient biasing means being in the form of a spring urging said latch member and said other latch member toward each other. 9. A key mechanism according to claim 8, and further comprising:

first and second guideways each receiving portions of said latch member and said other latch member for slidable movement relative to each other, a central stop abutment located between said guideways, said latch member having a shoulder formed thereon for engagement with said abutment, said other latch member having a shoulder formed thereon for engagement with said abutment, and said spring urging said latch member and said other latch member into engagement with said abutment. 10. A key mechanism according to claim 9, wherein said latch member and said other latch member have identical configurations.

11. A key mechanism according to claim 10, wherein said latch member and said other latch member each have dimples formed thereon for separating each other. 

1. A key member comprising: a first key adapted to be moved between a rest and an actuated position, a second key adapted to be moved between a rest and an actuated position, first latching means adapted to retain said first key in the actuated position, second latching means adapted to retain said second key in the actuated position, means resiliently biasing said first and second latching means toward each other, means associated with said first and second latching means whereby when the first key is moved to the actuated position the second key will assume a rest position and when the second key is moved to the actuated position the first key will assume the rest position.
 2. The key mechanism of claim 1, wherein the first and second keys are each provided with a flange, and said means associated with the first and second keys are camming surfaces disposed in the first and second latching means responsive to the motion of the flanges provided with the first and second keys.
 3. The key mechanism of claim 2, wherein said first and second latching means are provided with means for retaining the first and second keys in the rest positions.
 4. The key mechanism of claim 3, wherein said retaining means are hook formations disposed in the first and second latching means.
 5. A key mechanism, comprising: first and second key members each arranged for a depressible movement from a rest position to an actuated position and having a flange formed thereon, a latch member moveable relative to the depressible movements of said first and second key members and having a hook formation for latching engagement with the flange of said first key member at the actuated position, said latch member having first and second camming surfaces for engagement by the flanges of said first and second key members respectively with the first camming surface leading to the hook formation, said latch member undergoing a camming movement upon engagement of the first camming surface by the latching flange of said first key member during a depressible movement of said first key member to the actuated position, resilient biasing means urging against the camming movement effected by the depression of said first key member and moving the hook formation into latching engagement with the flange of said first key member upon movement of the flange past the first camming surface so as to hold said first key member at the actuated position, and said latch member undergoing another camming movement for releasing said first key member upon engagement of the second camming surface by the flange of said second key member during a depressible movement of said second key member to the actuated position, another latch member moveable relative to the Depressible movements of said first and second key members and having a hook formation for latching engagement with the flange of said second key member at the actuated position, said other latch member having first and second camming surfaces for engagement by the flanges of said first and second key members respectively with the second camming surface leading to the hook formation, said other latch member undergoing a camming movement upon engagement of the second camming surface by the latching flange of said second key member during a depressible movement of said second key member to the actuated position, said resilient biasing means urging against the camming movement effected by the depression of said second key member and moving the hook formation into latching engagement with the flange of said second key member upon movement of the flange past the second camming surface so as to hold said second key member at the actuated position, and said other latch member undergoing another camming movement for releasing said second key member upon engagement of the first camming surface by the flange of said first key member during a depressible movement of said first key member to the actuated position.
 6. A key mechanism according to claim 5, and further comprising: first and second guideways each receiving portions of said latch member and said other latch member for slidable movement relative to each other, a central stop abutment located between said guideways, said latch member having a shoulder formed thereon for engagement with said abutment, said other latch member having a shoulder formed thereon for engagement with said abutment, and said spring urging said latch member and said other latch member into engagement with said abutment.
 7. A key mechanism according to claim 5, wherein said latch member and said other latch member have identical configurations.
 8. A key mechanism according to claim 5; said latch member and said other latch member being arranged for slidable movement relative to each other and undergoing camming movements in opposite directions, and said resilient biasing means being in the form of a spring urging said latch member and said other latch member toward each other.
 9. A key mechanism according to claim 8, and further comprising: first and second guideways each receiving portions of said latch member and said other latch member for slidable movement relative to each other, a central stop abutment located between said guideways, said latch member having a shoulder formed thereon for engagement with said abutment, said other latch member having a shoulder formed thereon for engagement with said abutment, and said spring urging said latch member and said other latch member into engagement with said abutment.
 10. A key mechanism according to claim 9, wherein said latch member and said other latch member have identical configurations.
 11. A key mechanism according to claim 10, wherein said latch member and said other latch member each have dimples formed thereon for separating each other. 